Lifting apparatus and bed provided with the same

ABSTRACT

A lifting apparatus includes an upper frame, a base frame, a link mechanism for connecting the upper frame and the base frame, and a linear actuator connected to the link mechanism for driving the link mechanism. The link mechanism includes at least a T-shaped first arm slidably supported on the base frame or the upper frame and provided with connections at four points, and an L-shaped second arm provided with connections at three points.

BACKGROUND OF THE INVENTION

The present invention relates to a lifting apparatus for converting alinear action by a linear actuator into a linear action in a differentdirection, and a bed provided with the same.

There is a lifting apparatus for linearly lifting and lowering a heavyitem (for example, refer to Patent Literature 1 (JP 7-8481 A)). Thislifting apparatus is formed by, for example, a linear actuator includingan excellent thrust force and an X-shaped link structure.

FIG. 6 shows a configuration view of the conventional lifting apparatusdescribed in Patent Literature 1.

As shown in FIG. 6, a lifting apparatus 70 is formed by a foundation 71,a top plate 72, linear arms 74, 76, and a linear actuator 77. One end ofthe linear arm 74 is rotatably connected to the foundation 71, and theother end is connected slidably in a groove 73 of the top plate 72. Oneend of the linear arm 76 is rotatably connected to the top plate 72, theother end is connected slidably in a groove 75 of the foundation 71, anda center part is rotatably connected to the linear arm 74. One end ofthe linear actuator 77 is connected to the foundation 71, and the otherend is connected to the linear arm 76. This lifting apparatus 70 is amechanism of lifting and lowering the top plate 72 vertically withrespect to the foundation 71.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a lifting apparatus inwhich a load applied to an actuator is as constant as possible withoutdepending on a distance between an upper frame (top plate) and a baseframe (foundation), and a bed provided with the same.

In accomplishing these and other aspects, according to one aspect of thepresent invention, there is provided a lifting apparatus comprising alink mechanism lifting and lowering an upper frame with respect to abase frame, wherein

-   -   the link mechanism comprises:    -   a first arm slidably supported on the base frame or the upper        frame, the first arm including first, second, and third        connections placed on a first straight line in order, and a        fourth connection positioned on a second straight line which is        inclined by a predetermined angle with respect to the first        straight line from the second connection;    -   a second arm including fifth and sixth connections, and a        seventh connection positioned on a fourth straight line which is        inclined by a predetermined angle with respect to a third        straight line connecting the fifth and sixth connections, the        fourth straight line passing through the sixth connection; and    -   a fifth arm connected to the fourth connection of the first arm,    -   the second connection of the first arm and the sixth connection        of the second arm are rotatably connected,    -   a linear actuator has one end connected to the fifth connection        and the other end connected to the seventh connection of the        second arm, and    -   by driving the link mechanism with using the linear actuator,        the upper frame is relatively lifted and lowered with respect to        the base frame.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of the present invention willbecome clear from the following description taken in conjunction withthe embodiments thereof with reference to the accompanying drawings, inwhich:

FIG. 1A is a configuration view of a lifting apparatus in an embodimentof the present invention;

FIG. 1B is a configuration view of the lifting apparatus in theembodiment of the present invention;

FIG. 2 is a view showing size definition of the lifting apparatus in theembodiment;

FIG. 3 is a perspective view showing a separation state of a separationtype bed in which the lifting apparatus of the embodiment is used;

FIG. 4A is a perspective view showing a bed state of the separation typebed in which the lifting apparatus of the embodiment is used;

FIG. 4B is a detailed segmentary view of the bed state of the separationtype bed of the embodiment;

FIG. 4C is a segmentary plan view of the bed state of the separationtype bed in the embodiment;

FIG. 5A is a view showing a lifting apparatus of a first differentconfiguration in the embodiment;

FIG. 5B is a view showing a lifting apparatus of a second differentconfiguration in the embodiment; and

FIG. 6 is a configuration view of a conventional lifting apparatus.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings. It should be noted that the sameconstituent elements will be given the same reference numerals, anddescription thereof will be omitted in some cases. For easyunderstanding, the drawings are schematic focusing on the constituentelements.

Embodiment

FIG. 1A is a configuration view of a lifting state of a liftingapparatus 10 according to one embodiment of the present invention. FIG.1B is a configuration view of a lowering state of the lifting apparatus10, and FIG. 2 is a view showing size definition of the liftingapparatus 10.

As shown in FIGS. 1A and 13, the lifting apparatus 10 of the embodimentis a lifting apparatus for lifting and lowering an upper frame 11 withrespect to a base frame 12. This lifting apparatus 10 includes at leastthe base frame 12, the upper frame 11, a linear actuator 18, and a linkmechanism 80.

The link mechanism 80 includes a first arm 13, a second arm 14, a thirdarm 15, a fourth arm 16, and a fifth arm 17 as one example. The firstarm 13 is one example of a driving side T-shaped arm, and the second arm14 is one example of a driving side L-shaped arm. The third arm 15 isone example of a driven side T-shaped arm, the fourth arm 16 is oneexample of a driven side I-shaped arm, and the fifth arm 17 is oneexample of a rod shape conjunction arm.

The upper frame 11 includes a first protruding portion 22 a fixed to afront end thereof, a second protruding portion 21 a fixed in thevicinity of the first protruding portion 22 a, a third protrudingportion 27 a fixed to a portion behind the second protruding portion 21a, and a fourth protruding portion 26 a fixed in the vicinity of aportion behind the third protruding portion 27 a and in a rear end ofthe upper frame. The second protruding portion 21 a has a groove 21 bextending in the longitudinal direction parallel to the upper frame 11.By disengageably engaging a first pivot point 20 to be described laterinto the groove 21 b so that the first pivot point 20 can move slidablyin the groove 21 b, a slide guide 21 is formed. The first pivot point 20is, for example, a driving side upper slide pivot point (support axis).The fourth protruding portion 26 a has a groove 26 b extending in thelongitudinal direction parallel to the upper frame 11. By disengageablyengaging a seventh pivot point 25 to be described later into the groove26 b so that the seventh pivot point 25 can move slidably in the groove26 b, a slide guide 26 is formed. The seventh pivot point 25 is, forexample, a driven side upper slide pivot point (support axis).

The base frame 12 is arranged so as to face the upper frame 11. The baseframe 12 includes a fifth protruding portion 19 a fixed so as to facethe first protruding portion 22 a of the upper frame 11, and a sixthprotruding portion 24 a fixed so as to face the third protruding portion27 a of the upper frame 11. Therefore, a mounting surface 12 x of thebase frame 12 and a loading surface 11 x of the upper frame 11 arearranged so as to be vertical to a straight line connecting a secondpivot point 19 and a third pivot point 22 to be described later. Themounting surface 12 x of the base frame 12 and the loading surface 11 xof the upper frame 11 are arranged so as to be vertical to a straightline connecting an eighth pivot point 24 and a ninth pivot point 27 tobe described later. The second pivot point 19 is, for example, a drivingside lower fixed pivot point (support axis). The third pivot point 22is, for example, a driving side upper fixed pivot point (support axis).The eighth pivot point 24 is, for example, a driven side lower fixedpivot point (support axis). The ninth pivot point 27 is, for example, adriven side upper fixed pivot point (support axis). The loading surface11 x is, for example, a lifting item contact surface for loading alifting item.

As shown in FIGS. 1A and 1B, when seen from a side surface, the upperframe 11 is arranged in parallel with the base frame 12. In detail, whenseen from the side surface, the loading surface 11 x of the upper frame11 is arranged in parallel with the mounting surface 12 x of the baseframe 12.

The link mechanism 80 is arranged between the upper frame 11 and thebase frame 12. The link mechanism 80 is formed by various arms (thefirst arm 13, the second arm 14, the third arm 15, the fourth arm 16,and the fifth arm 17). This link mechanism 80 functions as one exampleof a link mechanism, and lifts and lowers the upper frame 11 withrespect to the base frame 12.

The link mechanism 80 is formed by a first link mechanism 80 a and asecond link mechanism 80 b. The first link mechanism 80 a is, forexample, a driving side link mechanism, and the second link mechanism 80b is, for example, a driven side link mechanism.

The first link mechanism 80 a is formed by at least the first arm 13 andthe second arm 14. The second link mechanism

Bob is formed by at least the third arm 15 and the fourth arm 16. Thefirst arm 13 and the third arm 15 each are one example of a T-shapedarm. The second arm 14 is one example of an L-shaped arm. The fourth arm16 is one example of an I-shaped arm.

The T-shaped arm is provided with connections at four points. Theconnections at four points of the T-shaped arm are connections at threepoints placed on a first straight line, and an offset connection at onepoint positioned on a second straight line which is inclined by apredetermined angle with respect to the first straight line from thecenter connection.

Connections at four points of the first arm 13 are a first connection 13a, a second connection 13 b, a third connection 13 c, and a fourthconnection 13 d. Specifically, these connections at four points areconnections at three points placed on the first straight line SL1between an upper end part and a lower end part of the first arm 13 (thefirst connection 13 a, the second connection 13 b, and the thirdconnection 13 c), and an offset connection (the fourth connection 13 d)at one point positioned on a second straight line SL2 which is inclinedby a predetermined angle θ1 with respect to the first straight line SL1from the center second connection 13 b. The first connection 13 a is thesecond pivot point 19, the second connection 13 b is a fourth pivotpoint 23, the third connection 13 c is the first pivot point 20, and thefourth connection 13 d is a fifth pivot point 29.

Connections at four points of the third arm 15 are an eighth connection15 a, a ninth connection 15 b, a tenth connection 15 c, and an eleventhconnection 15 d. Specifically, these connections at four points areconnections at three points placed on a first straight line SL5 betweenan upper end part and a lower end part of the third arm 15 (the eighthconnection 15 a, the ninth connection 15 b, and the tenth connection 15c), and an offset connection (the eleventh connection 15 d) at one pointpositioned on a second straight line SL6 which is inclined by apredetermined angle θ2 with respect to the first straight line SL5 fromthe center ninth connection 15 b. The eighth connection 15 a is theeighth pivot point 24, the ninth connection 15 b is a tenth pivot point28, the tenth connection 15 c is the seventh pivot point 25, and theeleventh connection 15 d is an eleventh pivot point 30.

The L-shaped arm is provided with connections at three points. Theconnections at three points of the L-shaped arm are connections at twopoints, and an offset connection at one point positioned on a fourthstraight line which is inclined by a predetermined angle with respect toa third straight line connecting the connections at two points.

Connections at three points of the second arm 14 are a fifth connection14 a, a sixth connection 14 b, and a seventh connection 14 c.Specifically, these connections at three points are connections (thefifth connection 14 a and the sixth connection 14 b) at two pointsplaced on a third straight line SL3 between an upper end part and anintermediate part of the second arm 14, and an offset connection (theseventh connection 14 c) at one point positioned on a fourth straightline SL4 which is inclined by a predetermined angle θ3 with respect tothe third straight line SL3. The fifth connection 14 a is the thirdpivot point 22, the sixth connection 14 b is the fourth pivot point 23,and the seventh connection 14 c is a sixth pivot point 32.

It should be noted that the L-shaped arm can function as a T-shaped armby extending a part thereof. Therefore, the L-shaped arm in thisembodiment includes the T-shaped arm. For example, although described indetail later, an eighth arm 211 of FIG. 5B is a modification of thesecond arm 14.

The I-shaped arm is provided with connections at two points in both endsof the longitudinal direction.

The fourth arm 16 is provided with connections at two points in bothends in the longitudinal direction, that is, a twelfth connection 16 ain an upper end part, and a thirteenth connection 16 b in a lower endpart. The twelfth connection 16 a is the ninth pivot point 27, and thethirteenth connection 16 b is the tenth pivot point 28.

The first connection 13 a serving as the lower end part of the first arm13 is rotatably connected to the fifth protruding portion 19 a of thebase frame 12 at the second pivot point 19. The third connection 13 cserving as the upper end part of the first arm 13 is connected to theupper frame 11 slidably by the slide guide 21. Specifically, bydisengageably engaging the first pivot point 20 into the groove 21 b ofthe second protruding portion 21 a of the upper frame 11, the thirdconnection 13 c of the first arm 13 is slidably connected to the upperframe 11.

The fifth connection 14 a serving as the upper end part of the secondarm 14 is rotatably connected to the first protruding portion 22 a ofthe upper frame 11 at the third pivot point 22. The sixth connection 14b of the second arm 14 is rotatably connected to the second connection13 b of the first arm 13 at the fourth pivot point 23. The fourth pivotpoint 23 is, for example, a driving side arm connection pivot point(support axis).

The eighth connection 15 a serving as the lower end part of the thirdarm 15 is rotatably connected to the sixth protruding portion 24 a ofthe base frame 12 at the eighth pivot point 24. The tenth connection 15c serving as the upper end part of the third arm 15 is connected to theupper frame 11 slidably by the slide guide 26. Specifically, bydisengageably engaging the seventh pivot point 25 into the groove 26 bof the fourth protruding portion 26 a of the upper frame 11, the tenthconnection 15 c serving as the upper end part of the third arm 15 isslidably connected to the upper frame 11.

The twelfth connection 16 a serving as the upper end part of the fourtharm 16 is rotatably connected to the third protruding portion 27 a ofthe upper frame 11 at the ninth pivot point 27. The thirteenthconnection 16 b serving as the lower end part of the fourth arm 16 isrotatably connected to the ninth connection 15 b of the third arm 15 atthe tenth pivot point 28. The tenth pivot point 28 is, for example, adriven side arm connection pivot point (support axis)

A driving side end part of the fifth arm 17 is rotatably connected tothe fourth connection 13 d of the first arm 13 at the fifth pivot point29. The fifth pivot point 29 is, for example, a driving side lowercoupling arm pivot point (support axis). A driven side end part of thefifth arm 17 is rotatably connected to the eleventh connection 15 d ofthe third arm 15 at the eleventh pivot point 30. The eleventh pivotpoint 30 is, for example, a driven side lower coupling arm pivot point(support axis). An end part 18 b of the linear actuator 18 is rotatablyconnected to an actuator fixing portion 31 of the fifth arm 17 in thevicinity of the driving side end part. The actuator fixing portion 31 ispositioned between the fifth pivot point 29 and the eleventh pivot point30.

One end part 18 b of the linear actuator 18 is rotatably connected tothe actuator fixing portion 31 on the fifth arm 17, and the other endpart 18 a is rotatably connected to the seventh connection 14 c of thesecond arm 14 at the sixth pivot point 32. The sixth pivot point 32 is,for example, a driving side lower coupling arm pivot point (supportaxis). The linear actuator 18 is connected to any arms of the linkmechanism 80 (the first arm 13, the second arm 14, the third arm 15, thefourth arm 16, and the fifth arm 17), so as to drive to lift and lowerthe upper frame 11 with respect to the base frame 12.

As shown on the left side of FIG. 2, a distance between center of thesecond pivot point 19 and center of the fourth pivot point 23 is definedas L1. A distance between center of the first pivot point 20 and thecenter of the fourth pivot point 23 is defined as L2. A distance betweencenter of the fifth pivot point 29 and the center of the fourth pivotpoint 23 is defined as L3. A distance between center of the sixth pivotpoint 32 and the center of the fourth pivot point 23 is defined as L7. Adistance between center of the third pivot point 22 and the center ofthe fourth pivot point 23 is defined as L8. A predetermined angle madeby a straight line (part of the first straight line SL1) connecting thecenter of the first pivot point 20 and the center of the fourth pivotpoint 23 and a straight line (the second straight line SL2) connectingthe center of the fifth pivot point 29 and the center of the fourthpivot point 23 is defined as θ1. A predetermined angle made by astraight line (the third straight line SL3) connecting the center of thesixth pivot point 32 and the center of the fourth pivot point 23 and astraight line (the fourth straight line SL4) connecting the center ofthe third pivot point 22 and the center of the fourth pivot point 23 isdefined as θ3. An angle made by a straight line connecting the thirdpivot point 22 and the fourth pivot point 23 and a straight lineconnecting the second pivot point 19 and the fourth pivot point 23 isdefined as θ11. An angle made by a straight line connecting the fifthpivot point 29 and the fourth pivot point 23 and a straight lineconnecting the sixth pivot point 32 and the fourth pivot point 23 isdefined as θ12. It should be noted that in the embodiment, the secondpivot point 19, the first pivot point 20, and the fourth pivot point 23are arranged on the same straight line (the first straight line SL1).

Further, as shown on the right side of FIG. 2, a distance between centerof the eighth pivot point 24 and center of the tenth pivot point 28 isdefined as L4. A distance between center of the seventh pivot point 25and the center of the tenth pivot point 28 is defined as L5. A distancebetween center of the eleventh pivot point 30 and the center of thetenth pivot point 28 is defined as L6. A distance between center of theninth pivot point 27 and the center of the tenth pivot point 28 isdefined as L9. A predetermined angle made by a straight line (part ofthe first straight line SL5) connecting the center of the seventh pivotpoint 25 and the center of the tenth pivot point 28 and a straight line(the second straight line SL6) connecting the center of the eleventhpivot point 30 and the center of the tenth pivot point 28 is defined asθ2. It should be noted that in the embodiment, the center of the eighthpivot point 24, the center of the seventh pivot point 25, and the centerof the tenth pivot point 28 are arranged on the same straight line (thefirst straight line SL5)

When the inventors variously examined regarding the lifting apparatus 10formed in such a way, it was found that by setting the configuration ofthe link mechanism 80 under a predetermined condition, a load applied tothe linear actuator 18 by a heavy item loaded on the loading surface 11x of the upper frame 11 becomes substantially constant without dependingon a position (height) of the upper frame 11. Specifically, it was foundthat with a triangular-shape formed by the fourth pivot point 23, thesecond pivot point 19, and the third pivot point 22, and atriangular-shape formed by the fourth pivot point 23, the fifth pivotpoint 29, and the sixth pivot point 32 as similar shapes in FIG. 2, theload applied to the linear actuator 18 becomes substantially constantwithout depending on the position (height) of the upper frame 11.Further specifically, it was found that with L1=L8 and L3=L7 and theangle θ11=θ12 in FIG. 2, the load applied to the linear actuator 18becomes substantially constant without depending on the position(height) of the upper frame 11. It should be noted that at this time, inthe link mechanism 80, L1=L2=L8=L4=L5=L9, L3=L7=L6, and the angleθ1=θ2=θ3=90°. In the link mechanism 80 of the embodiment, thetriangular-shape formed by the fourth pivot point 23, the second pivotpoint 19, and the third pivot point 22, and a triangular-shape formed bythe tenth pivot point 28, the ninth pivot point 27, and the eighth pivotpoint 24 have the same shape.

Further, it was found that at this time, as the angle θ1 (=θ3) is moredifferent from 90°, the load applied to the linear actuator 18 inaccordance with the position of the upper frame 11 is changed more.

It should be noted that the load applied to the linear actuator 18 isobtained by multiplying the load by the heavy item loaded on the loadingsurface 11x of the upper frame 11 by a constant calculated by L1/L3.

In the embodiment, the triangular-shape formed by the fourth pivot point23, the sixth pivot point 32, and the fifth pivot point 29, and thetriangular-shape formed by the third pivot point 22, the fourth pivotpoint 23, and the second pivot point 19 are isosceles triangular-shapeshaving an apex angle of 2α (=θ11=θ12) which are similar shapes. Theangle α is an angle made by the loading surface 11 x of the upper frame11 or the mounting surface 12 x of the base frame 12 and L1 or L2 (thefirst straight line SL1).

The linear actuator 18 is arranged so as to connect the sixth pivotpoint 32 and the fifth pivot point 29. A change amount of a distancebetween the sixth pivot point 32 and the fifth pivot point 29 is a driveamount of the linear actuator 18. A distance between the third pivotpoint 22 and the second pivot point 19 is lifting height, and a changeamount of the distance between the third pivot point 22 and the secondpivot point 19 is a lifting amount. Therefore, a ratio between the driveamount of the linear actuator 18 and the lifting amount is L1/L3. As aresult, the load applied to this lifting apparatus 10 becomes alwaysconstant without depending on the angle α.

It should be noted that in the embodiment, positional relationshipsbetween the pivot points of the third arm 15 are the same as the firstarm 13 with L1=L4, L2=L5, L3=L6, and θ1=θ2. Regarding the second arm 14and the fourth arm 16, L8=L9.

FIG. 3 is a perspective view of a separation type bed 40 in which thelifting apparatus 10 of the embodiment is used. FIG. 4A is a perspectiveview of the time when the separation type bed 40 is deformed into a bedstate. FIG. 4B is an enlarged segmentary view in the perspective view ofthe separation type bed 40. FIG. 4C is an enlarged segmentary view in aplan view of the separation type bed 40.

As shown in FIG. 3, the separation type bed 40 is formed by a bed unit50 and a wheelchair unit 60.

The bed unit 50 includes the above lifting apparatus 10 inside thereof,and is formed in such a manner that a support member in an upper part ofthe bed unit 50 is lifted and lowered by the lifting apparatus 10 withrespect to a base of the bed unit 50. The support member of the bed unit50 is a member for supporting a mattress or the like on which a userlies. The wheelchair unit 60 is stored in a storage space 51 provided ina part on one side in the width direction in the bed unit 50 so as toform the bed state. In this bed state, the wheelchair unit 60 is liftedand lowered together with the upper frame 11 by the lifting apparatus10. In the bed unit 50, the fifth arm 17 and the linear actuator 18 arearranged only on one side (on the far side in FIG. 3) in the widthdirection of the bed unit 50 but not arranged on the other side (on thenear side in FIG. 3) in the width direction of the bed unit 50 where thestorage space 51 is provided. With such a configuration, the largestorage space 51 is ensured in the bed unit 50.

The wheelchair unit 60 includes two armrests 61, an operation unit 62provided in a front end of one of the armrests 61 (on the side oppositeto the bed unit 50 at the time of combination), a seat unit 63 to bedeformed from a chair form into a flat form by an input of the operationunit 62, and four wheels 64 for moving the wheelchair unit 60.

The separation type bed 40 of the embodiment can be deformed from aseparated state in which the bed unit 50 and the wheelchair unit 60 areseparated into the bed state in which the bed unit 50 and the wheelchairunit 60 are combined and the entire surfaces of the bed unit 50 and thewheelchair unit 60 are brought into a flat form, by moving thewheelchair unit 60 to the storage space 51 by the input of the operationunit 62 by an operator, and then bringing the seat unit 63 into a flatform. As shown in FIG. 4A, the separation type bed 40 deformed into thebed state integrally lifts and lowers the bed unit 50 and the wheelchairunit 60 at the same time by the lifting apparatus 10 provided insidethereof.

Side rails 65 are installed on side surfaces of the separation type bed40, and the user can be prevented from falling from the side surfaces ofthe separation type bed 40 by the side rails 65. As shown in FIGS. 4Band 4C, the side rails 65 are inserted into side rail holders 66provided in the bed unit 50 and the wheelchair unit 60 from the side.

FIG. 5A is a configuration view of a lifting apparatus 100 serving as adifferent configuration of the lifting apparatus 10 and a firstdifferent configuration of the embodiment. FIG. 5B is a configurationview of a lifting apparatus 200 serving as a different configuration ofthe lifting apparatus 10 and a second different configuration of theembodiment.

As shown in FIG. 5A, the lifting apparatus 100 serving as the firstdifferent configuration of the embodiment includes an upper frame 11, abase frame 12, a first arm 13, a second arm 14, a sixth arm 111, aseventh arm 112, a fifth arm 17, and a linear actuator 18. That is, thelifting apparatus 100 serving as the first different configuration has adifferent driven side arm configuration from the above lifting apparatus10. The second arm 14 and the seventh arm 112 are respectively oneexample of the L-shaped arm, and the sixth arm 111 is one example of theI-shaped arm. The first arm 13 and the second arm 14 are a first linkmechanism. The sixth arm 111 and the seventh arm 112 are a second linkmechanism. The sixth arm 111 has a fourteenth connection 111 a, afifteenth connection 111 b, and a sixteenth connection 111 c in order onone straight line SL8 obliquely upward from the lower side. The seventharm 112 has a seventeenth connection 112 a and an eighteenth connection112 b arranged in order obliquely downward from the upper side, and anineteenth connection 112 c positioned on a straight line SL10 which isinclined by a predetermined angle θ4 with respect to a straight line SL9connecting the seventeenth connection 112 a and the eighteenthconnection 112 b, the straight line passing SL10 through the eighteenthconnection 112 b. The angle θ4 is the same angle as the angle θ3.

The fifteenth connection 111 b of the sixth arm 111 and the eighteenthconnection 112 b of the seventh arm 112 are rotatably connected at afourteenth pivot point 114. In the lifting apparatus 100, a sixth pivotpoint 32 of the second arm 14 and a thirteenth pivot point 115 of theseventh arm 112 are connected by the fifth arm 17. An actuator fixingportion 31 on the fifth arm 17 and a fifth pivot point 29 of the firstarm 13 are connected by the linear actuator 18.

In the lifting apparatus 100 of the first different configuration,lengths of the arms are the same i.e. the straight line SL8=the straightline SL5, the straight line SL9=the straight line SL7, and the straightline SL10=the straight line SL4. Therefore, a triangular-shape formed bya fourth pivot point 23, a second pivot point 19, and a third pivotpoint 22, and a triangular-shape formed by the fourteenth pivot point114, a ninth pivot point 27, and an eighth pivot point 24 have the sameshape. A triangular-shape formed by the fourth pivot point 23, the sixthpivot point 32, and the third pivot point 22, and a triangular-shapeformed by the fourteenth pivot point 114, the ninth pivot point 27, andthe thirteenth pivot point 115 have the same shape.

Regarding the fifth pivot point 29 or the sixth pivot point 32, thedirection of the pivot point not connected to the linear actuator 18with respect to the pivot point connected to the linear actuator 18 isdefined as a determination direction 113. By arranging the actuatorfixing portion 31 of the lifting apparatus 100 in the opposite directionto the determination direction 113 with respect to the pivot pointconnected to the linear actuator 18, the direction of a load applied tothe linear actuator 18 in the lifting apparatus 100 is reversed from theload applied to the linear actuator 18 in the above lifting apparatus10, so that a tensile load is added. As a result, the lifting apparatus100 of the first different configuration is particularly effective in acase where the linear actuator 18 has a favorable characteristic withrespect to tension.

As shown in FIG. 5B, the lifting apparatus 200 serving as the seconddifferent configuration of the embodiment is formed by an upper frame11, a base frame 12, a first arm 13, an eighth arm 211, a fifth arm 17,and a linear actuator 18. That is, the lifting apparatus 200 serving asthe second different configuration has only a driving side armconfiguration without a driven side arm configuration, and has adifferent driving side arm configuration from the above liftingapparatus 10. Each of the first arm 13 and the eighth arm 211 is oneexample of the T-shaped arm. The eighth arm 211 is the modification ofthe second arm 14.

In the lifting apparatus 200, the eighth arm 211 is connected to othermembers at a third pivot point 22, a twelfth pivot point 212, a fourthpivot point 23, and a sixth pivot point 32. Specifically, the eighth arm211 is rotatably coupled to the upper frame 11 at the third pivot point22, slidably connected to a slide guide 213 provided in the base frame12 at the twelfth pivot point 212, and rotatably coupled to the firstarm 13 at the fourth pivot point 23. The slide guide 213 has a similarstructure to the slide guide 21. That is, the base frame 12 has a fixedprotruding portion 213 a, the protruding portion 213 a has a groove 213b extending in the longitudinal direction, and the twelfth pivot point212 is disengageably engaged into the groove 213 b so as to be slidablymovable, thereby forming the slide guide 213. The twelfth pivot point212 is, for example, a driving side lower slide pivot point (supportaxis). The fifth arm 17 is rotatably connected to a fifth pivot point 29of the first arm 13.

In the lifting apparatus 200 of the second different configuration, atriangular-shape formed by the fourth pivot point 23, a second pivotpoint 19, and the third pivot point 22, and a triangular-shape formed bythe fourth pivot point 23, a fifth pivot point 29, and the sixth pivotpoint 32 are similar shapes. In the second different configuration, whenthe sum of an angle (θ1) made by a segment (first straight line)connecting the second pivot point 19 and a first pivot point 20 and asegment (second straight line) connecting the fourth pivot point 23 andthe fifth pivot point 29, and an angle (θ3) made by a segment (thirdstraight line) connecting the third pivot point 22 and the twelfth pivotpoint 212 and a segment (fourth straight line) connecting the fourthpivot point 23 and the sixth pivot point 32 is 180°, a load applied tothe linear actuator 18 by a heavy item loaded on a loading surface 11 xof the upper frame 11 can be substantially constant without depending ona distance between the upper frame 11 and the base frame 12. That is, inthe second different configuration, with θ1+θ3=180°, the load applied tothe linear actuator 18 can be constant.

In the lifting apparatus 200, by connecting the linear actuator 18 tothe sixth pivot point 32 of the eighth arm 211 and an actuator fixingportion 31 of the fifth arm 17, the load applied to the linear actuator18 by the heavy item loaded on the loading surface 11 x of the upperframe 11 can be substantially constant without depending on the distancebetween the upper frame 11 and the base frame 12.

According to the above embodiment, the lifting apparatus in which theload applied to the linear actuator 18 becomes constant withoutdepending on the distance between the upper frame 11 and the base frame12, and the bed provided with the same can be provided.

By appropriately combining arbitrary embodiments or modifications amongthe above various embodiments and modifications, effects provided in theembodiments or the modifications can be obtained.

It should be noted that although the example of the bed provided withthe lifting apparatus is described in the embodiment, the liftingapparatus of the present invention can be utilized for various devicesprovided with a lifting device in addition to the bed.

The lifting apparatus according to the present invention and the bedprovided with the same are particularly useful for a nursing care bedfor lifting and lowering a care-receiver within a wide range, and usefulin an ordinary house, a hospital facility, or a nursing care facilitywhere the care-receiver in need of care resides.

Although the present invention has been fully described in connectionwith the embodiments thereof with reference to the accompanyingdrawings, it is to be noted that various changes and modifications areapparent to those skilled in the art. Such changes and modifications areto be understood as included within the scope of the present inventionas defined by the appended claims unless they depart therefrom.

What is claimed is:
 1. A lifting apparatus comprising a link mechanismlifting and lowering an upper frame with respect to a base frame,wherein the link mechanism comprises : a first arm slidably supported onthe base frame or the upper frame, the first arm including first,second, and third connections placed on a first straight line in order,and a fourth connection positioned on a second straight line which isinclined by a predetermined angle with respect to the first straightline from the second connection; a second arm including fifth and sixthconnections, and a seventh connection positioned on a fourth straightline which is inclined by a predetermined angle with respect to a thirdstraight line connecting the fifth and sixth connections, the fourthstraight line passing through the sixth connection; and a fifth armconnected to the fourth connection of the first arm, the secondconnection of the first arm and the sixth connection of the second armare rotatably connected, a linear actuator has one end connected to thefifth connection and the other end connected to the seventh connectionof the second arm, and by driving the link mechanism with using thelinear actuator, the upper frame is relatively lifted and lowered withrespect to the base frame.
 2. The lifting apparatus according to claim1, wherein a triangular-shape formed by the second connection, the fifthconnection, and the first connection, and a triangular-shape formed bythe second connection, the fourth connection, and the seventh connectionare similar shapes.
 3. The lifting apparatus according to claim 1,wherein the first arm is a T-shaped arm, and the second arm is anL-shaped arm.
 4. The lifting apparatus according to claim 2, wherein thefirst arm is a T-shaped arm, and the second arm is an L-shaped arm. 5.The lifting apparatus according to claim 1, wherein the secondconnection is positioned in center of a segment connecting the firstconnection and the third connection.
 6. The lifting apparatus accordingto claim 2, wherein the second connection is positioned in center of asegment connecting the first connection and the third connection.
 7. Thelifting apparatus according to claim 1, wherein the link mechanismcomprises: a first link mechanism on a driving side connected to thelinear actuator, the first link mechanism including the first arm andthe second arm; and a second link mechanism on a driven side, and thefifth arm connects the first link mechanism and the second linkmechanism.
 8. The lifting apparatus according to claim 2, wherein thelink mechanism comprises: a first link mechanism on a driving sideconnected to the linear actuator, the first link mechanism including thefirst arm and the second arm; and a second link mechanism on a drivenside, and the fifth arm connects the first link mechanism and the secondlink mechanism.
 9. The lifting apparatus according to claim 7, whereinthe second link mechanism comprises: a T-shaped third arm slidablysupported on the base frame or the upper frame, the third arm includingeighth, ninth, and tenth connections placed on the first straight linein order, and an eleventh connection positioned on the second straightline which is inclined by a predetermined angle with respect to thefirst straight line from the second connection; and an I-shaped fourtharm including twelfth and thirteenth connections, and the ninthconnection of the third arm and the thirteenth connection of the fourtharm are rotatably connected.
 10. The lifting apparatus according toclaim 8, wherein the second link mechanism comprises: a T-shaped thirdarm slidably supported on the base frame or the upper frame, the thirdarm including eighth, ninth, and tenth connections placed on the firststraight line in order, and an eleventh connection positioned on thesecond straight line which is inclined by a predetermined angle withrespect to the first straight line from the second connection; and anI-shaped fourth arm including twelfth and thirteenth connections, andthe ninth connection of the third arm and the thirteenth connection ofthe fourth arm are rotatably connected.
 11. The lifting apparatusaccording to claim 7, wherein the second link mechanism comprises: asixth arm including fourteenth, fifteenth, and sixteenth connections;and a seventh arm including seventeenth and eighteenth connections, anda nineteenth connection positioned on a fifth straight line which isinclined by a predetermined angle with respect to a sixth straight lineconnecting the seventeenth and eighteenth connections, the fifthstraight line passing through the eighteenth connection, and thefifteenth connection of the sixth arm and the eighteenth connection ofthe seventh arm are rotatably connected.
 12. The lifting apparatusaccording to claim 8, wherein the second link mechanism comprises: asixth arm including fourteenth, fifteenth, and sixteenth connections;and a seventh arm including seventeenth and eighteenth connections, anda nineteenth connection positioned on a fifth straight line which isinclined by a predetermined angle with respect to a sixth straight lineconnecting the seventeenth and eighteenth connections, the fifthstraight line passing through the eighteenth connection, and thefifteenth connection of the sixth arm and the eighteenth connect ion ofthe seventh arm are rotatably connected.
 13. The lifting apparatusaccording to claim 1, wherein the link mechanism comprises the firstarm, and a T-shaped eighth arm formed on the third straight lineconnecting the fifth and sixth connections in the second arm andextended so as to have another connection on an opposite side of thefifth connection with respect to the sixth connection.
 14. The liftingapparatus according to claim 2, wherein the link mechanism comprises thefirst arm, and a T-shaped eighth arm formed on the third straight lineconnecting the fifth and sixth connections in the second arm andextended so as to have another connection on an opposite side of thefifth connection with respect to the sixth connection.
 15. The liftingapparatus according to claim 1, wherein the predetermined angle is 90°.16. The lifting apparatus according to claim 2, wherein thepredetermined angle is 90°.
 17. The lifting apparatus according to claim1, wherein a sum of an angle made by the first straight line and thesecond straight line, and an angle made by the third straight line andthe fourth straight line is 180°.
 18. The lifting apparatus according toclaim 2, wherein a sum of an angle made by the first straight line andthe second straight line, and an angle made by the third straight lineand the fourth straight line is 180°.
 19. A bed, comprising: the liftingapparatus according to claim 1; and a bed unit to be lifted and loweredby the lifting apparatus.
 20. A bed, comprising: the lifting apparatusaccording to claim 2; and a bed unit to be lifted and lowered by thelifting apparatus.